Radio interference suppression means for engines



April 13, 1954 w. w. CUSHMAN 2,675,415

RADIO INTERFERENCE SUPPRESSION MEANS FOR ENGINES Filed Dec. 3, 1952 Mum-.1

INVENTOR aliozz "(Cuskmazz' Patented Apr. 13, 1954 UNITED STATES PATENT OFFICE RADIO INTERFERENCE SUPPRESSION MEANS FOR ENGINES (Granted under Title 35, U.- S. Code (1952),

see. 266) 7 Claims.

The invention described. herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to means for preventing radio interference and the like, due to the operation of the high tension ignition elements of internal combustion engines and the like.

A primary object of the invention is to provide a casing or housing for the high tension elements of the ignition system of an internal combustion engine, the casing also rendering the ignition elements Waterproof.

A further object of the invention is to provide a casing or housing of the above-mentioned character which is held in place during the operation of the engine by the suction created in the intake manifold of the engine.

A still further object is to provide a device of the above-mentioned character which is more effective for suppressing radio interference caused by engines than somewhat similar devices of the prior art.

Still another object is to provide means of the above-mentioned character which are highly simplified construction, and inexpensive to manufacture.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like throughout the same,

Figure 1 is a side elevation of an internal combustion engine having my radio interference suppression means applied thereto,

Figure 2 is a plan view of the same,

Figure 3 is a transverse vertical section on line 33 of Figure 1,

Figure l is an exploded perspective view of the interference suppression means removed, and,

Figure 5 is an enlarged fragmentary vertical section on line 5-5 of Figure 2.

In the drawings, where for the purpose of illustration is shown a preferred embodiment of the invention, the numeral it designates generally an internal combustion engine of any preferred type, such as a well known type of automotive engine. The engine it comprises a body portion l3, and an intake manifold I4 is 2 mounted upon one side of the cylinder block I! near the top of the same, as shown. An exhaust manifold I5 is arranged below the intake manifold i l in the usual manner, and a carburetor ['6 is mounted above the intake manifold, as shown.

The high tension ignition elements of the engine are located at the side of the block ll remote from the intake manifold It, and these elements include a longitudinal row of spark plugs ll, arranged at an inclination, and seated upon an inclined surface or ledge 18 formed in the adjacent side of the block H, Figure 3. The usual distributor housing It is mounted upon the same side of the block ll, near the longitudinal center of the same and below the spark plugs l7, and the distributor housing may likewise be inclined, as shown in the drawings. Insulated wires 20 lead from the top of the distributor housing 19 to the several spark plugs ii, and are electrically connected therewith in the usual manner. A spark coil M is held by a bracket 22, near one side of the distributor housing Ill, and below the spark plugs ll, and the bracket 22 is rigidly secured to the adjacent side or" the cylinder block H. The spark plu s ll, distributor housing !9, wires 20 and spark coil 22! comprise the high tension ignition elements to be shielded and covered by the radio interference suppression means of the present invention. This means comprises a relatively shallow pan-like cover or casing of relatively light gage sheet metal, and the cover 23 is preferably rectangular as viewed, from the side, Figure 1, and has its inner side next to the block ll entirely open. The cover :23 has an outer flat side 24, vertically disposed in use and an inclined marginal wall 25, integral with the outer side Integrally secured to the marginal edge of the inclined wall 25, and extending continuously about the entire rectangular margin of the cover 23 is a rigid U- shapedchannel or connecting part 28, having an open side facing in the same direction as the open side of the cover 23, Figure 5. The open side of the channel 26 projects laterally beyond the marginal edge of the inclined wall 25, Figure 5.

A companion rigid ill-shaped channel El, som what wider than the channel 25 is rigidly secured by screws 28 or the like to the adjacent side of the cylinder block I l, and this channel 21 also extends continuously about the entire rectangular margin of the cover 23, and may encompass substantially the entire vertical side of the block II. The channels 26 and 21 are 3 inverted, relative to each other, and adapted to be arranged in opposed interfitting relation, as shown in Figure 5, with the channel 26 arranged innermost. A continuous compressible fiat gasket 29 of lead or the like is arranged in the bottom of the channel 21 and extends throughout the entire length of the channel, and this gasket is engaged by the forward edges of the sides 30 of channel 26, as shown. It may be seen that a relatively small chamber or passage 3| is formed by the interfitting channels 26 and 21, and this passage is adapted to be gastight, by virtue of the engagement of the channel sides 30 with the lead gasket 29.

In order to create a partial vacuum within the marginal passage 3|, I mount a screw-threaded tubular nipple or fitting 32 within the outer vertical side of the channel 26, at any convenient point upon the channel, and a section tube 33 of rubber or the like, connected with the nipple 32 leads upwardly and across the top of the cover I2, and downwardly to the intake manifold l4, Figure 3. A nipple 3 mounted within the top of the intake manifold is connected with the other end of the tube 33, so that the suction formed within the intake manifold M when the engine operates will produce a partial vacuum within the passage 3|.

In order to secure the cover 23 to the cylinder block I when the engine is not operating, a plurality of screws 35 such as the three screws 35 shown in Figure l, are arranged at suitably spaced points about the margin of the cover 23, and these screws 35 have screw-threaded engagement within screw-threaded openings formed in the adjacent side of the cylinder block II. An equal number of small apertured tabs or lugs 36 are integrally secured to outer vertical side of the channel 26, and project laterally outwardly of the channels 26 and 21, as shown. The apertured tabs 36 receive the several screws 35, in the manner shown, and this arrangement provides adequate support for the cover 23, which is quite light, when the engine is not operating.

In operation, when the engine is operating and the high tension ignition elements, including the distributor I9, spark plugs l1 and spark coil 2| are propagating radio interference waves, a rather strong partial vacuum is formed in the passage 3|, and the channel 26 is drawn into gastight engagement with the gasket 29. It should be mentioned, as an important feature of the invention that by creating the partial vacuum between the channels 26 and 21, rather than inside the entire cover 23, collapsing of the cover 23 under the effect of the vacuum is prevented. This collapsing of the cover would occur otherwise, as the cover is formed of thin sheet metal, because of the rather high degree of suction created in the intake manifold M. Without the arrangement of the interfitting channels for forming the relatively small passage 3|, it would become necessary to form the cover 23 from unduly heavy gage sheet metal, to resist the effect of the partial vacuum.

During the operation of the engine, when the partial vacuum is created in the passage 3|, the cover 23 has a gastight seal with the cylinder block I and there are no cracks or openings for the escape of the radio interference waves. Also, while the engine is operating a completely watertight enclosure for the high tension ignition elements is afforded by the cover 23, and this is highly advantageous. When the engine is not operating, no partial vacuum is created in the passage 3|, and the cover 23 may not have a gastight connection with the block However, at this time there is no radio interference wave propagation caused by the engine, and as soon as the engine is started, the partial vacuum within the passage 3| will immediately seal the cover 23 against the gasket 29, thus making the ignition system watertight, and also effectively preventing the emanation of radio interference waves. As previously stated, when the engine is not operating, and there is no vacuum in the passage 3|, the screws 35 serve to secure the cover 23 to the side of the block Although I have shown and described the radio interference suppression means including the cover 23 associated with one preferred type of engine, it is not intended to limit the application of the means to any particular type of internal combustion engine, and obviously, my means are readily adaptable to various types of internal combustion engines by merely changing the shape of the cover or housing, in the necessary manner, to enclose the several high tension ignition elements of the engine. Likewise, the interfitting channels 26 and 21 need not be shaped to encompass a rectangular area, as shown in Figure 1, but may likewise be formed to extend over any desired surface or surfaces of the various internal combustion engines to which my radio interference suppression means is applicable, and it is not intended to limit the invention to a particular engine, as previously stated.

It is to be understood that the form of the invention, herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or scope of the subjoined claims.

I claim:

1. Means for suppressing radio interference waves caused by the ignition elements of an internal combustion engine comprising a cover for the ignition elements of the engine, passage forming means carried by the cover near the margin thereof, and means connected with the passage forming means and with the intake manifold of the engine for creating a partial vaccum in the passage forming means when the engine operates and thereby drawing the cover into substantially gastight engagement with the engine.

2. Means for suppressing radio interference waves caused by the ignition elements of an internal combustion engine comprising a cover for the ignition elements of the engine, a marginal channel part secured to the cover and engaging the engine and forming therewith a marginal passage, and means connected with said marginal channel part and with the intake manifold of the engine for creating a partial vacuum within said marginal passage when the engine operates, whereby the cover is drawn into substantially gastight engagement with the engine,

3. Means for suppressing radio interference waves caused by the high tension ignition elements of an engine comprising a cover to be arranged over the high tension ignition elements for enclosing the same, a first channel secured to the margin of the cover and having an open side, a second channel secured to the engine and surrounding said high tension ignition elements and having an open side and adapted to receive the open side of the first channel. a gasket arranged in the bottom of the second channel for engagement with the first channel and forming therewith a passage extending longitudinally of the first and second channels, and a tube connected to the first channel and in the intake manifold of the engine so that the passage is evacuated when the engine operates for producing a substantially gastight enclosure for the high tension ignition elements.

4. Means for suppressing radio interference waves caused by the high tension ignition elements of an engine of the type having said ignition elements arranged upon one side of the engine comprising a cover for engagement over said high tension ignition elements and adapted to enclose the same, a first marginal channel carried by the cover and having an open side directed toward said side of the engine, a second marginal channel secured to said side of the engine and having an open side directed toward and receiving the open side of the first channel, a compressible gasket arranged between the first and second channels and forming with the first channel a passage extending longitudinally of the first channel, a tube connected with the intake manifold of the engine and with the first channel for creating a partial Vacuum within said passage when the engine is operating, and separate attaching means connected with said cover for securing it to the engine while the engine is idle.

5. Means for suppressing radio interference waves caused by the ignition elements of an engine comprising a sheet metal cover for the ignition elements and having an open side to receive the elements, a marginal part secured to the cover adjacent to the open side of the same, a com panion marginal part secured to the engine and adapted to interfit with the marginal part of the cover and to form therewith a relatively small gastight marginal passage about the cover, and conduit means connected with the intake manifold of the engine and communicating with said relatively small marginal passage for causing a partial vacuum therein when the engine operates and thereby forming a substantially gastight connection between the cover and engine.

6. Means for suppressing radio interference waves caused by the ignition elements of an internal combustion engine, comprising an imperforate one-piece cover having a closed top and depending side and end walls, said cover disposed over the ignition elements of the engine with the free edges of the side and end walls contiguous the body of the engine, sealing means between the free edges of said walls and the body of the engine, and means providing a fluid connection between the cover and the intake manifold of the engine, whereby the cover is drawn against and hermetically sealed to the body of the engine when the latter is in operation.

'7. Means for suppressing radio interference waves caused by the ignition elements of an internal combustion engine, comprising an imperforate one-piece cover having a closed top and depending side and end walls, said cover disposed over the ignition elements of the engine with the free edges of the side and end walls contiguous the body of the engine, sealing means between the free edges of said walls and the body of the engine, and means providing an unobstructed fluid connection between the cover and the intake manifold of the engine, whereby the cover is drawn against and hermetically sealed to the body of the engine when the latter is in operation.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,659,528 Hosterman Feb. 14, 1928 2,073,871 Kliesrath Mar. 16, 1937 2,149,516 Flamm Mar. 7, 1939 FOREIGN PATENTS Number Country Date 638,543 Great Britain June '7, 1950 

